Control for wire feed



March 25, 1958 R. A. KRAAY ET AL CONTROL FOR WIRE FEED Filed May 21, 1954 United States Patent CONTROL FOR WIRE FEED Robert A. Kraay, South.H0lland,.and Erwin J. Reiner, Palos- Park, lll.,,assignors to Western Electric Company, Incorporated, New York, N. Y., a corporation of This invention relates to acontrol system for a wire feed .and more particularly to a vwire feed electronic .control device for maintaining a loop of. straightened wire within predetermined minimum and maximum .lengths from which the wire may be withdrawn as needed.

.An object of the invention is to provide a wire feed control device operable in response to movement to predetermined positions of a loop of wire being fed.

. Another object of the invention is to provide a wire feed control device for rendering said wire feed operable. by the closing of a circuit component thereof through a portion of the wire in response to the move ment of a loop of wire to a first predetermined position and for rendering said wire feed inoperable by .the closing of another circuit component thereof through a portion of the wire in response to the movement of .wire to a second predetermined position.

A still further object ofthe invention is to provide a wire feed control actuatable by engagement of the .1 wiretherewith under substantially zero contact pressure.

A device illustrating certain features of the invention for controlling the actuation of a wire feed in accordance ,withthe size of a wire loop formed therebymay include a relay associated with the wire feedfor rendering it operative and inoperative in response to energization and deenergization of said relay, and a controlcircuit including a pair of contacts mounted to engage the loop I of wire when the loop has reached predetermined minimum and maximum lengths for effecting the energization and deenergization of the relay. The control circuit includes a pair of triodes connected to a source of power and having their cathodes connected to ground and their grids individually connected to said pair of contacts, and the plate of one triode connected to said relay for-energiz ing said relay when said one triode is conducting.

. The wire being fed is grounded, whereby when the size of the loop changes and the loop of wire is moved into engagement with one of the contacts the grid connected thereto is brought to the same potential as the cathode associated therewith and renders the triode conductive,

, -:and a network interconnecting said triodes is operable in response to one of said tubes becoming conductive to apply a zero potential to the grid of the tube which is conducting to maintain it conductive, and to apply a negative bias to the grid of the other tube to render it non-conductive. This condition remains until the loop of wire moves intoengagement with the other contact which serves to reverse the operating conditions of the tubes and of the wire feed.

Other objects and advantages of the invention will become apparent by reference to the following detailed description and the accompanying drawings illustrating a preferred embodiment thereof, in which Fig. 1 is a diagrammatic side elevational view of a portion of the apparatus for feeding wire to a wire processing apparatus;

2,828,455 Patented Mar. 25, 1958 Y .,Fig. 2 is a circuit diagram of the electric control de- ..vice for the wire feed; and

. Fig. 3 is a side elevational view of a pair of contacts of the control device engageable with a loop of the wire being fed. Referring to the drawings, represents a portion of an apparatus for molding blocks of insulating material started and stopped by means under control of a relay 25. The relay has an armature 26 stressed to a normal closed position in engagement with a pair of contacts 27 when the relay is deenergized to effect the closing of the motor circuit and it has a coil 28 for retracting the armature 26 to effect the opening of the motor circuit in response to energization of the relay. The looped portion 13 of the wires form a supply of straightened wire from which wire is intermittently withdrawn by the molding apparatus as needed.

It is desirable that a constant supply of straightened wire be maintained at all times by the looped portions 13 .and that the loops 13- should be within. predetermined maximum and minimum lengths having predetermined upper and lower limits'aud that-the wires should not 25 to open the motor circuit and stop the wire feed to the straightener 15 when the loop 13 falls to the position indicated in full lines in Fig. 1 and to deenergize the relay'25 to effect the closing of the motor circuit and the feeding of the wire when the loop 13 rises to the upper position shown in dotted lines therein.

The control device or circuit includes an upper contact 30 positioned to engage one of the wires at its upper limit of movement and a lower contact 31 positioned to engage the wire 12 at its lower limit of movement. The contacts 30 and 31 are in the form of elongated metal strips mounted on a standard 32 of insulating material with the faces of the contacts 30 and31 vertically aligned with the face 33 of the standard 32'to form a continuous substantially straight surface 34 for the loop 13 of wire to slide upon. The standard 32 is positioned between a pair of wires with the surface 34 disposed laterally of the normal position of the loop of the selected control wire to cause the loop 13 to continuously bear against the surface 34 with a very slight pressure. This light pressure of the wire against the contacts 30, 31 and the standard 32 is substantially of zero value and is insufficient to bend it from its straightened con dition but is suflicient to establish a suitable electrical connection between the wire and the contacts for effecting actuation of the control device;

The control circuit includes a pair of identical triode tubes 35 and 36 which may be enclosed in a single or in individual envelopes as desired. The grid 37 of the triode 35 is electrically connected to the lower contact 31 and the grid 38 of the triode 36 is connected to the upper contact 30. The cathodes 39 and 40 of the triodes are electrically connected to the wire 12 by suitably grounding them and the wire supply. Plate voltage is supplied to. the triodes by an electronic power supply 41 comprising a transformer 43 connected to a power line 44, a rectifier tube 45, and a two-section RC filter 46.

3 secondary 47 of the transformer supplies current for heating the cathodes of the tubes 35, 36, and 45.

The relay coil 28 and a resistor 48 are connected in series in the plate circuit of the triode 35, and a resistor 50 substantially equivalent in value to the resistance "of the coil 28 and the resistor 48 is connected in the l'plate circuit of the triode 36. One end of a resistor 53 is connected at point 54 to the plate 49 and the other end thereof is connected at point 55 to the grid 51 of the triode 36 and to one end of a resistor 56. The other end of the resistor 56 is connected at point 57 to the lead 58 of the power supply 41 and to one end of a resistor 59, the other end of which is connected to ground. One end of a resistor 60 is connected at point 61 to theplate 51 of the triode 36 and the other end thereof is connected at point 62 to the grid 37 of the triode 35 and to one end of resistor 59.

The resistors 50, 60, 63, 59, and the resistors 48, 53, 56, 59, and the coil 28 form a pair of voltage dividers which constitutes a network interconnected with the triodes 35 and 36 in a manner so as to render one triode nonconductive while the other is conductive and to maintain said other tube conductive until the loop 13 of wire has moved from engagement with one of the contacts 30, 31 into engagement with the other to reverse the operating conditions of the triodes. V g

It we assume that the wire feed is operating, the loop 13 of wire gradually increases until it is lowered to the point where it engages the lower contact 31 as shown in Fig. l, at which time the wire 13 connects the grid of the triode 35 to ground and brings it to the same potential as the cathode thereof and thereby causes the triode 35 to conduct and energize the relay 25, thus rendering the Wire feed inoperative. With the triode 35 conducting, the voltage drop across the resistor 48 and the coil 23 causes the voltage of the triode 35 to fall from a high positive value, as for example, +160 volts to a lower positive value, as for example, +60 volts. At point 57 of the voltage divider including the resistors 53 and 56 the voltage is at a high negative value, as for example, 40 volts due to the voltage drop across the resistor 59 as a result of the cathode current of the triode 35. The voltage at point 55 derived from this divider and applied to the grid of the triode 35 is sufiiciently negative to hold this tube cut off. The plate 51 of the triode 36 under these conditions is at +160 volts and the voltage at point 62, the junction of resistors 60 and 63, is at ground and maintains triode 35 conductive until the loop of wire 13 is moved upwardly into engagement with the upper contact 30. Thus, while the triode 35 is conducting the relay 25 is actuated and the wire feed remains inoperative until the wire feed of the molding apparatus has withdrawn a sufficient length of straightened wire from the loop 13 to cause it to be raised into engagement with the upper contact 3@ as indicated in dotted lines in Fig. l at which time the triode conditions are reversed, triode 36 is rendered conductive and the triode 39 non-conductive and the relay is deenergized to cause the motor circuit to be closed, thus rendering the wire feed operative.

From the above description it will be seen that a bistable flip-lop or multi-vibrator control circuit is provided for reflecting the starting and the stopping of the wire feed in response to movement of the Wire loop 13 into engagement alternately with the upper and the lower contacts 3% and 31 which areconnected to the control inputs orgrid 37 and 38 of the circuit.

It is to beunderstood that the above-described arrangements are simply illustrative of the application of the principles of this invention. Numerous otherarr'angements may be readilydevised bythose skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof.

What is claimed is: a r

1. In a system for controlling the feed of a strand,

means for feeding the strand and maintaining a storage loop in the fed strand, a relay for controlling the feeding means to control the size of the loop, means for selectively operating the relay to control the feeding means including a bi-stable multi-vibrator circuit connected to the strand and having a pair of control inputs for changing said circuit from one stable condition to the other, and a pair of contacts connected to the control inputs and positioned for engaging the loop of said strand as it increases and decreases to predetermined limits for completing circuits through a portion of the strand and the control inputs alternately to change the multi-vibrator circuit from one stable condition to the other.

2. A device for controlling the actuation of a wire feed in accordance with the movement of a loop in the wire alternately from one to the other of a pair of predetermined positions comprising means including a relay for rendering said wire feed operative and inoperative in response to energization and deenergization of said relay, a bi-stable multi-vibrator circuit for energizing and deenergizing said relay, said multi-vibrator circuit being connected to said wire and having a pair of control inputs for changing the circuit from one stable condition to another, and contacts connected to said control inputs for engaging said loop of wire alternately in said predetermined positions to complete circuits through a portion of the wire andthe control inputs to change the condition of the multi-vibrator circuit and the relay.

3. A device for controlling the actuation of a wire feed in accordance with the size of a wire loop formed thereby comprising a pair of contacts mounted to engage the loop of wire when the loop has reached predetermined minimum and'maximum sizes, means including a relay for rendering said wire feed operative and inoperative, apair of triodes having their cathodes connected to ground and their grids individually connected to said contacts and the plate of one triode connected to said relay for actuating said relay in response to said one triode becoming conductive, means for supplying power to said triodes, means for grounding said wire whereby when the loop of wire is moved into engagement with one of said contacts the grid connected thereto is brought to the same potential as the cathode of the triode associated With said grid and renders the triode conductive, and a network interconnecting said triodes operable in response to one of said tubes becoming conductive to apply a zero bias to the grid of the tube which is conducting to maintain it conductive and a negative bias to the grid of the other tube to render it non-conductive.

4. A device for controlling the actuation of a wire feed in accordance with the size of a wire loop formed thereby comprising means including a relay for rendering said wire feed operative and inoperative in response to energization and deenergization of said relay, circuit means including a pair of triodes connected to a power supply and having the relay connected in the plate circuit of one or" said triodes, means including a portion of said wire for electrically connecting the grid to the cathode of one triode to render it conductive in response to the movement of said loop to a first predetermined position, means including a portion of said wire for electrically connecting'the grid to the cathode of the other triode to render it conductive in response to the movement of said loop to a second predetermined position, and a network interconnecting said triodes and operable in response to a'tube becoming conductive to apply zero bias to the grid of the tube which is conducting to maintain it conductive and to apply a negative bias to the grid of the other tube to render it non-conductive.

5. A device for controlling the actuation of a wire feed in accordance with the size of a wire loop formed thereby comprising means including a relay for rendering said wire feed operative and inoperative in response to energizing and deenergizing said relay, a pair of triodes having their cathodes connected to said wire and the plate of one triode connected to said relay for energizing said relay in response to said one triode becoming conductive, means for supplying power to said triodes, a network interconnecting said triodes operable in response to a tube becoming conductive to apply zero bias to the grid of the tube which is conducting and to apply a negative bias to the grid of the other tube to render it non-conductive, and a pair of contacts electrically connected individually to the grids of said triodes and mounted to engage the loop of wire when the loop has reached predetermined minimum and maximum sizes whereby in response to engagement of the wire alternately with the contacts the tubes are alternately rendered conductive and non-conductive.

6. In a system for controlling the feed of a wire to provide a storage loop therein, the combination of means for feeding a w're, means having a substantially vertically disposed surface engageable with the loop of wire and having a pair of vertically spaced contacts provided with substantially vertically disposed surfaces engageable with the loop of wire with substantially zero contact pressure as the loop is moved to and from predetermined upper and lower positions, control means electrically connected to said wire and including a pair of electronic tubes having grids connected to said contacts and operable for rendering said electronic tubes alternately conducting and non-conducting in response to the movement of said loop of wire into engagement alternately with said contacts, and means operable in response to the conduction of one of said tubes for rendering said feeding means operative.

7. In a system for controlling the feed of a wire to provide a storage loop therein, the combination of means for feeding a wire, electronic means for rendering said feeding means alternately operative and inoperative in response to movement of said loop to predetermined lower and upper positions, said electronic means being electrically connected to said wire and having a first contact and a circuit capable of being completed through a portion of said wire for effecting the actuation of said electronic means to render said feed means operative in response to movement of said loop of wire into en gagement with said first contact, said electronic means having a second contact and a circuit capable of being completed through a portion of said wire for elfecting the actuation of said electronic means to render said feed inoperative in response to movement of said loop of wire into engagement with said second contact, and means for supporting said contacts in vertically spaced relation to each other and in substantially vertically disposed positions for sliding engagement of said wire loop therewith in said predetermined lower and upper positions and with substantially zero pressure, said supporting means having a guide surface engageable with said wire loop for guiding said wire loop for movement up and down into engagement with said contacts.

8. In a system for controlling the feed of a wire, means for feeding the wire to form a storage loop therein, a relay for controlling the feeding means to control the size of the loop, a bi-stable multi-vibrator circuit for energizing and dcenergizing said relay, said multi-vibrator circuit being connected to said wire and having a pair of control inputs for changing the circuit from one condition to another to energize and deenergize said relay, a stationary upright dielectric member engageable with the loop as it moves to and from predetermined upper and lower positions, and contacts connected to said contrcl inputs and mounted on said dielectric member for engaging slidably said loop of Wire in said predetermined positions to complete circuits through a portion of the wire and the control inputs alternately to change the condition of the multi-vibrator circuit.

References Cited in the file of this patent UNiTED STATES PATENTS 2,147,421 Bendz Feb. 14, 1939 2,193,189 Brooke Mar. 12, 1940 2,296,488 Anderson Sept. 22, 1942 2,317,921 Leach Apr. 27, 1943 2,487,755 Few Nov. 8, 1949 2,512,372 Pakala June 20, 1950 

